Modern state-of-the-art techniques have clear limitations on the imaging of the smallest nanoparticles, making it difficult for researchers to study viruses and other structures at the molecular level.
Researchers from the University of Houston and the University of Texas, MD Anderson Cancer Center report in Nature Communications a new technology for optical imaging of nanoscale objects, relying on scattered light to detect nanoparticles up to 25 nanometers in diameter. The technology, known as PANORAMA, uses a glass object coated with gold nanodisks, which allows scientists to monitor changes in light transmission and determine the characteristics of the target.
PANORAMA is named after Plasmonic Nano-aperture Label-Imaging (PlAsmonic NanO-aperture lAbel-iMAging), which means the key features of the technology. PANORAMA can be used to detect, count and size individual dielectric nanoparticles.
Wei-Chuan Shi, a professor of electrical engineering and computer engineering at UH and author of the article, said that the smallest transparent object that a standard microscope can display is between 1
Labeling is another commonly used technique; requires researchers to know something about the particle they are studying – for example, that the virus has a protein jump – and to create a way to label this feature with a fluorescent dye or some other method to make it easier to detect the particle.
“Otherwise, it will look invisible like a little speck under a microscope because it’s too small to detect,” Shea said.
Another drawback? Labeling is only useful if researchers already know at least something about the particle they want to study.
“With PANORAMA, you don’t have to do the labeling,” Shea said. “You can see it directly because PANORAMA does not rely on the detection of scattered light from the nanoparticle.”
Instead, the system allows observers to detect a transparent target as small as 25 nanometers by observing the transmission of light through a gold nanodisc-coated glass object. By observing changes in light, they can detect nearby nanoparticles. The optical imaging system is a standard bright field microscope, common in every laboratory. There is no need for lasers or interferometers, which are required in many other labelless imaging technologies.
“According to the data, the size limit has not been reached. We opted for 25 nm nanoparticles, simply because these are the smallest polystyrene nanoparticles on the market,” Shi said.
Higher resolution images of living, moving cells using plasmonic metasurfaces
Nareg Ohannesian et al. Plasmonic image without nanoaperture label (PANORAMA), Nature Communications (2020). DOI: 10.1038 / s41467-020-19678-w
Provided by the University of Houston
Quote: The new technology allows a more accurate view of the smallest nanoparticles (2020, November 16), retrieved on November 17, 2020 from https://phys.org/news/2020-11-technology-precise-view- smallest-nanoparticles.html
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